nv2a: Implement texture LOD bias

Fixes #767

Tests: https://github.com/abaire/nxdk_pgraph_tests/blob/2aa0cb89543f3853a3830ba15a03c9f7dad58d69/src/tests/texture_lod_bias_tests.h#L1
HW results: https://abaire.github.io/nxdk_pgraph_tests_golden_results/results/Texture_LOD_Bias/index.html

Author: abaire

hw/xbox/nv2a/pgraph/gl/renderer.h

@@ -80,6 +80,7 @@ typedef struct TextureBinding {
     bool border_color_set;
     GLenum gl_target;
     GLuint gl_texture;
+    uint32_t lod_bias;
 } TextureBinding;
 
 typedef struct ShaderModuleCacheKey {

hw/xbox/nv2a/pgraph/gl/texture.c

@@ -107,6 +107,15 @@ static bool check_texture_possibly_dirty(NV2AState *d,
     return possibly_dirty;
 }
 
+static inline float convert_lod_bias(uint32_t lod_bias)
+{
+    int sign_extended_bias = lod_bias;
+    if (lod_bias & (1 << 12)) {
+        sign_extended_bias |= ~NV_PGRAPH_TEXFILTER0_MIPMAP_LOD_BIAS;
+    }
+    return (float)sign_extended_bias / 256.f;
+}
+
 static void apply_texture_parameters(TextureBinding *binding,
                                      const BasicColorFormatInfo *f,
                                      unsigned int dimensionality,
@@ -120,6 +129,8 @@ static void apply_texture_parameters(TextureBinding *binding,
     unsigned int addru = GET_MASK(address, NV_PGRAPH_TEXADDRESS0_ADDRU);
     unsigned int addrv = GET_MASK(address, NV_PGRAPH_TEXADDRESS0_ADDRV);
     unsigned int addrp = GET_MASK(address, NV_PGRAPH_TEXADDRESS0_ADDRP);
+    unsigned int lod_bias =
+        GET_MASK(filter, NV_PGRAPH_TEXFILTER0_MIPMAP_LOD_BIAS);
 
     if (f->linear) {
         /* somtimes games try to set mipmap min filters on linear textures.
@@ -146,6 +157,10 @@ static void apply_texture_parameters(TextureBinding *binding,
                         pgraph_texture_mag_filter_gl_map[mag_filter]);
         binding->mag_filter = mag_filter;
     }
+    if (lod_bias != binding->lod_bias) {
+        binding->lod_bias = lod_bias;
+        glTexParameterf(binding->gl_target, GL_TEXTURE_LOD_BIAS, convert_lod_bias(lod_bias));
+    }
 
     /* Texture wrapping */
     assert(addru < ARRAY_SIZE(pgraph_texture_addr_gl_map));

hw/xbox/nv2a/pgraph/vk/texture.c

@@ -51,6 +51,15 @@ static VkSamplerAddressMode lookup_texture_address_mode(int idx)
     return pgraph_texture_addr_vk_map[idx];
 }
 
+static inline float convert_lod_bias(uint32_t lod_bias)
+{
+    int sign_extended_bias = lod_bias;
+    if (lod_bias & (1 << 12)) {
+        sign_extended_bias |= ~NV_PGRAPH_TEXFILTER0_MIPMAP_LOD_BIAS;
+    }
+    return (float)sign_extended_bias / 256.f;
+}
+
 // FIXME: Move to common
 // FIXME: We can shrink the size of this structure
 // FIXME: Use simple allocator
@@ -1356,7 +1365,8 @@ static void create_texture(PGRAPHState *pg, int texture_idx)
                                        VK_SAMPLER_MIPMAP_MODE_LINEAR,
         .minLod = mipmap_en ? MIN(state.min_mipmap_level, state.levels - 1) : 0.0,
         .maxLod = mipmap_en ? MIN(state.max_mipmap_level, state.levels - 1) : 0.0,
-        .mipLodBias = 0.0,
+        .mipLodBias = convert_lod_bias(
+            GET_MASK(filter, NV_PGRAPH_TEXFILTER0_MIPMAP_LOD_BIAS)),
         .pNext = sampler_next_struct,
     };